Methods for treating diseased or injured tissue by implanting into the tissue at a site of the disease or injury a porous freeze-dried fibrin matrix formed from plasma proteins. The proteins include fibrinogen cleaved by the action of thrombin at varying concentrations sufficient to cleave the fibrinogen and Factor XIII. The matrix has less than 10% residual moisture and is devoid of exogenous anti-fibrinolytic agents, plasminogen and of organic chelating agents. Alternatively, the plasma proteins comprise partially purified plasma proteins that are devoid of plasminogen.
